Re: [Elecraft] Noise from KAT500?

[Steve L]

There have been several tests in QST of switching power supplies in the past - 
including analysis of RF noise they create which was actually scary.  Some are 
better than others, but all generate RF noise.  

I second the vote for non-switching (i.e. linear) supply from Astron (or 
equivalent) and eliminating all of the “wall wart” style supplies you can.

Steve
AA8AF

> On Dec 3, 2023, at 2:41 PM, G4GNX  wrote:
> 
> Then purchase a 12V PSU from a reputable Ham Radio dealer, who is unlikely to 
> sell you a noisy one.
> 

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Re: [Elecraft] Noise from KAT500?

[G4GNX]

Send an email to:

elecraft-unsubscr...@mailman.qth.net 


73,
Alan - G4GNX
South Coast UK
Elecraft K4D / KPA500 / KAT500 / IC-9700




> On 4 Dec 2023, at 23:03, Masadaman via Elecraft  
> wrote:
> 
> How do I unsubscribe to this?
> 
> Sent from Yahoo Mail on Android 
> 
>  On Sun, Dec 3, 2023 at 8:14 PM, Jim Brown wrote: 
>   On 12/3/2023 4:20 PM, David Woolley wrote:
>> small, ferrite toroid. Using a higher frequency allows a less bulky 
>> transformer.
> 
> Yes.
> 
> 73, Jim K9YC
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Re: [Elecraft] Noise from KAT500?

[Masadaman via Elecraft]

How do I unsubscribe to this?

Sent from Yahoo Mail on Android 
 
  On Sun, Dec 3, 2023 at 8:14 PM, Jim Brown wrote:  
 On 12/3/2023 4:20 PM, David Woolley wrote:
> small, ferrite toroid. Using a higher frequency allows a less bulky 
> transformer.

Yes.

73, Jim K9YC
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Re: [Elecraft] Noise from KAT500?

[Wes]

Note Jim's words about a "good transmission line calculator" and take to heart 
Dan's ,AC6LA, words:



 "Think Twice Before Using a Web-Based Line Loss Calculator"

See his site here: https://ac6la.com/swrloss.html

Wes  N7WS

On 12/4/2023 12:50 PM, Jim Brown wrote:
Clarifying a typo, "antenna tuners" like the KAT500 are networks that 
transform the impedance presented by the transmission line to 50 ohms, 
allowing the output stage to provide power to the line. This has NO effect on 
loss in the line, which is determined solely by the match between the antenna 
and the line, as Bob correctly states.


That said, line loss due to SWR is often wildly overestimated. For 60M, I'm 
using an 80M dipole fed with about 160 ft of a good RG11, which looks like 5:1 
VSWR at the transmitter. Taking line loss into account, VSWR at the antenna is 
around 7:1. A good transmission line calculator shows the excess loss in the 
line due to VSWR to be about 1 dB, which is a small fraction of an S-unit. 
Using FT8, I've confirmed more than 70 countries on that band with 100W, and 
can work EU almost any night from my QTH near San Francisco.


73, Jim K9YC

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Re: [Elecraft] Noise from KAT500?

[Jim Brown]

Clarifying a typo, "antenna tuners" like the KAT500 are networks that 
transform the impedance presented by the transmission line to 50 ohms, 
allowing the output stage to provide power to the line. This has NO 
effect on loss in the line, which is determined solely by the match 
between the antenna and the line, as Bob correctly states.


That said, line loss due to SWR is often wildly overestimated. For 60M, 
I'm using an 80M dipole fed with about 160 ft of a good RG11, which 
looks like 5:1 VSWR at the transmitter. Taking line loss into account, 
VSWR at the antenna is around 7:1. A good transmission line calculator 
shows the excess loss in the line due to VSWR to be about 1 dB, which is 
a small fraction of an S-unit. Using FT8, I've confirmed more than 70 
countries on that band with 100W, and can work EU almost any night from 
my QTH near San Francisco.


73, Jim K9YC

On 12/4/2023 7:16 AM, Bob McGraw wrote:
The KPA500 at the station only matches the transmitter to the 
transmission line and likewise for the receiver.   It does not change 
the match between the antenna and transmission line, thus the SWR and 
related loss from SWR remains.


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Re: [Elecraft] Noise from KAT500?

[Jim Brown]

On 12/3/2023 4:20 PM, David Woolley wrote:
small, ferrite toroid. Using a higher frequency allows a less bulky 
transformer.


Yes.

73, Jim K9YC
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Re: [Elecraft] Noise from KAT500?

[David Woolley]

Most switch mode supplies have transformers. The weight differences 
reflects the difference between a large mass of laminated iron, and a, 
small, ferrite toroid. Using a higher frequency allows a less bulky 
transformer.


--
David Woolley

On 03/12/2023 04:54, David Gilbert wrote:


The ones I measured just a couple of months ago were way too small and 
light to have a transformer in them, and they were horrible.  In any 
case, I recommend that anyone using a wall wart for other than its 
intended equipment (or any standalone new one) be sure to check it for 
both noise and no load voltage regulation.  It's quick and easy to do 
and could save a lot of headaches.


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Re: [Elecraft] Noise from KAT500?

[Dave B via Elecraft]

To me, it sounds like that when the ATU is inline (& I presume you let 
it tune to that antenna at some point.  Yes/No?)
The antenna is better matched to the transmission line, so more of the 
on-air "ambient" noise is delivered to the RX.


I get the same here, where 60m is quite noisy anyway.  At times over 
some 10dB difference!  Even more noticeable on 80m and 160m.  Where the 
"bare" antenna (random wire sloper) is naturally even more inefficient.


Do you have a passive/manual ATU you could compare with, using the same 
RX and Antenna?


If it was SMPS noise, I'd expect (in your case) a 60 or 120Hz based buzz 
to be part of that "noise".  But I don't hear that.


73.

Dave G0WBX.



On 03/12/2023 15:52, elecraft-requ...@mailman.qth.net wrote:

Subject: [Elecraft] Noise from KAT500?


--
Sent from a MicroSoft free zone:
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Re: [Elecraft] Noise from KAT500?

[G4GNX]

Then purchase a 12V PSU from a reputable Ham Radio dealer, who is unlikely to 
sell you a noisy one.

73,
Alan - G4GNX
South Coast UK
Elecraft K4D / KPA500 / KAT500 / IC-9700




> On 3 Dec 2023, at 19:16, W2HX  wrote:
> 
> ?  I don't have any 12v transceivers. This is the only 12 device I have in 
> the shack.
> Thanks
> Eugene W2HX
> Sent from Nine
> 
> 
> From: Bob McGraw 
> Sent: Sunday, December 3, 2023 12:11 PM
> To: elecraft@mailman.qth.net
> Subject: [Elecraft] Noise from KAT500?
> 
> Just power it from the transceiver power supply and all will be
> resolved.   There is no point in making life complex.
> 
> 73
> 
> Bob, K4TAX

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Re: [Elecraft] Noise from KAT500?

[Jack Brindle via Elecraft]

I remember those days. I still have my Heath SB-303 and SB-401 pair, both of 
which run from 117VAC. I didn’t have to get a 12V supply until I started 
upgrading back around 2000.
You might want to invest in a small Astron linear supply (or similar). You will 
slowly start acquiring equipment that runs on 12 - 13.8VDC, so getting one now 
would be a good thing.
What kind of things? I love my Heath HM102, but modern SWR/Power bridge meters 
provide so much better info. This is just one example…

73!
Jack, W6FB


> On Dec 3, 2023, at 1:16 PM, W2HX  wrote:
> 
> ?  I don't have any 12v transceivers. This is the only 12 device I have in 
> the shack.
> Thanks
> Eugene W2HX
> Sent from Nine<http://www.9folders.com/>
> 
> 
> From: Bob McGraw mailto:rmcg...@benlomand.net>>
> Sent: Sunday, December 3, 2023 12:11 PM
> To: elecraft@mailman.qth.net <mailto:elecraft@mailman.qth.net>
> Subject: [Elecraft] Noise from KAT500?
> 
> Just power it from the transceiver power supply and all will be
> resolved.   There is no point in making life complex.
> 
> 73
> 
> Bob, K4TAX
> 
> 
> On 12/3/2023 9:52 AM, elecraft-requ...@mailman.qth.net wrote:
>> Message: 8
>> Date: Sun, 3 Dec 2023 01:48:45 +0000
>> From: W2HX
>> To: Michael Carter, Elecraft Reflector Reflector
>>   
>> Subject: Re: [Elecraft] Noise from KAT500?
>> Message-ID:
>>   
>> 
>> 
>> Content-Type: text/plain; charset="utf-8"
>> 
>> Mike, K8CN wins the cigar!
>> 
>> 
>> 
>> The issue is the power supply ? I took some spectrum analyzer plots to 7
>>  MHz and you can see what I saw. The set up is spectrum analyzer ->
>> KAT500 -> Dummy Load. First picture are two "max hold" traces
>> superimposed where the problem can be seen.
>> 
>> https://w2hx.com/x/Elecraft/KAT500/Noise-Issue/KAT500-AC-Power.png
>> 
>> The "lower" trace is what I saw with the kat500 in bypass. The "top"
>> trace is with the kat500 inline (auto or manual).
>> 
>> 
>> 
>> I then replaced the wall-wart power supply with a 12V battery. And this
>> is what I saw for BOTH bypass and inline. Clearly the problem.
>> 
>> https://w2hx.com/x/Elecraft/KAT500/Noise-Issue/KAT500-battery.png
>> 
>> using a battery, the noise is about -80 dBm. Using the wall-wart, in some 
>> cases the noise is as high as -60 dBm
>> 
>> 
>> 
>> My task now is to either leave it on battery or preferably, find a low noise 
>> PS.
>> 
>> 
>> 
>> Thanks everyone for the ideas.
>> 
>> 
>> 
>> 73 Eugene W2HX
>> 
>> Subscribe to my Youtube Channel:https://www.youtube.com/@w2hx/videos
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Re: [Elecraft] Noise from KAT500?

[W2HX]

?  I don't have any 12v transceivers. This is the only 12 device I have in the 
shack.
Thanks
Eugene W2HX
Sent from Nine<http://www.9folders.com/>


From: Bob McGraw 
Sent: Sunday, December 3, 2023 12:11 PM
To: elecraft@mailman.qth.net
Subject: [Elecraft] Noise from KAT500?

Just power it from the transceiver power supply and all will be
resolved.   There is no point in making life complex.

73

Bob, K4TAX


On 12/3/2023 9:52 AM, elecraft-requ...@mailman.qth.net wrote:
> Message: 8
> Date: Sun, 3 Dec 2023 01:48:45 +
> From: W2HX
> To: Michael Carter, Elecraft Reflector Reflector
>    
> Subject: Re: [Elecraft] Noise from KAT500?
> Message-ID:
>
> 
>
> Content-Type: text/plain; charset="utf-8"
>
> Mike, K8CN wins the cigar!
>
>
>
> The issue is the power supply ? I took some spectrum analyzer plots to 7
>   MHz and you can see what I saw. The set up is spectrum analyzer ->
> KAT500 -> Dummy Load. First picture are two "max hold" traces
> superimposed where the problem can be seen.
>
> https://w2hx.com/x/Elecraft/KAT500/Noise-Issue/KAT500-AC-Power.png
>
> The "lower" trace is what I saw with the kat500 in bypass. The "top"
> trace is with the kat500 inline (auto or manual).
>
>
>
> I then replaced the wall-wart power supply with a 12V battery. And this
> is what I saw for BOTH bypass and inline. Clearly the problem.
>
> https://w2hx.com/x/Elecraft/KAT500/Noise-Issue/KAT500-battery.png
>
> using a battery, the noise is about -80 dBm. Using the wall-wart, in some 
> cases the noise is as high as -60 dBm
>
>
>
> My task now is to either leave it on battery or preferably, find a low noise 
> PS.
>
>
>
> Thanks everyone for the ideas.
>
>
>
> 73 Eugene W2HX
>
> Subscribe to my Youtube Channel:https://www.youtube.com/@w2hx/videos
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Re: [Elecraft] Noise from KAT500?

[G4GNX]

Oh purleeez, don’t start a political argument on an Amateur Radio forum, 
especially without changing the subject line.

73,
Alan - G4GNX
South Coast UK
Elecraft K4D / KPA500 / KAT500 / IC-9700




> On 3 Dec 2023, at 15:28, Wes  wrote:
> 
> I know you are a fan of government running everything in our lives, but this 
> "small" government is $33+ trillion in debt.
> 
> On 12/2/2023 8:25 PM, Jim Brown wrote:
>> 
>> 99.9% of stuff that plugs into the wall has a Switch-mode power supply, most 
>> of which are varying degrees of noisy. They were mandated to save energy 
>> about 20 years ago, but thanks to small government, the FCC has no money to 
>> enforce their Rules that they be quiet. So they aren't.


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Re: [Elecraft] Noise from KAT500?

[Wes]

I know you are a fan of government running everything in our lives, but this 
"small" government is $33+ trillion in debt.


On 12/2/2023 8:25 PM, Jim Brown wrote:


99.9% of stuff that plugs into the wall has a Switch-mode power supply, most 
of which are varying degrees of noisy. They were mandated to save energy about 
20 years ago, but thanks to small government, the FCC has no money to enforce 
their Rules that they be quiet. So they aren't.

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Re: [Elecraft] Noise from KAT500?

[G4GNX]

FWIW I had this issue with an IC7100/MFJ 1500W tuner.

I was finding sprogs in the 40 metre band and they were changing frequency 
(moving round the band) when I changed the tuning frequency, which I put down 
to different relays being deployed, varying the load.
I replaced the PSU and all returned to normal.

I also have an AOC monitor that chucks noise over several HF bands on my K3S, 
due to an errant PSU. I don’t use it very often and not in the shack any more.

I run my K3S and ancillaries (including the KAT500) from a 60 amp (continuous 
rating) variable voltage SMPSU which is capable of 100 Amps for short periods. 
It’s well built and very quiet. That PSU has been in use for many years with no 
hint of trouble. I also use them on Theatre Organ consoles for the stops. There 
can be upwards of 400 stop magnets requiring 500mA each, usually for <50mS, so 
theoretically 200A could be drawn and on the odd occasion (usually under test) 
that a General Cancel is required for all tabs (stops) those PSUs just take it 
in their stride, and there’s been no QRM noticed on any nearby radio.

SMPSUs are absolutely fine if you choose carefully - the bigger the better. 
Wall warts are just a recipe for trouble. The only ones I use these days were 
supplied by Yaesu, rated at 12V 1A and they’re quiet across all loads I’ve 
presented them with.

Pleased that you’ve cured your issue.

73,
Alan - G4GNX
South Coast UK
Elecraft K4D / KPA500 / KAT500 / IC-9700




> On 3 Dec 2023, at 01:48, W2HX  wrote:
> 
> Mike, K8CN wins the cigar!
> 
> 
> 
> The issue is the power supply ☹ I took some spectrum analyzer plots to 7 MHz 
> and you can see what I saw. The set up is spectrum analyzer -> KAT500 -> 
> Dummy Load. First picture are two "max hold" traces superimposed where the 
> problem can be seen.
> 
> https://w2hx.com/x/Elecraft/KAT500/Noise-Issue/KAT500-AC-Power.png
> 
> The "lower" trace is what I saw with the kat500 in bypass. The "top" trace is 
> with the kat500 inline (auto or manual).
> 
> 
> 
> I then replaced the wall-wart power supply with a 12V battery. And this is 
> what I saw for BOTH bypass and inline. Clearly the problem.
> 
> https://w2hx.com/x/Elecraft/KAT500/Noise-Issue/KAT500-battery.png
> 
> using a battery, the noise is about -80 dBm. Using the wall-wart, in some 
> cases the noise is as high as -60 dBm
> 
> 
> 
> My task now is to either leave it on battery or preferably, find a low noise 
> PS.
> 
> 
> 
> Thanks everyone for the ideas.
> 
> 
> 
> 73 Eugene W2HX
> 

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Re: [Elecraft] Noise from KAT500?

[Dave (NK7Z)]

Bill,

At the risk of going a bit off topic from Elecraft here--  I use a power 
distribution block, and run 12 volts to every device I can reach from a 
known good supply.


For the items I can get to with that 12V I go to the local thrift 
stores, and look at the used wall wart power supplies.  I buy the heavy 
ones...


I then test them at home, both loaded and unloaded for voltage and RFI. 
If good I use them, if bad, I recycle them.  Most used PS at the thrift 
stores are cheap, and the heavy ones are usually transformer based, and 
RF quiet..


73, and thanks,
Dave (NK7Z)
https://www.nk7z.net
ARRL Volunteer Examiner
ARRL Technical Specialist, RFI
ARRL Asst. Director, NW Division, Technical Resources

On 12/2/23 21:19, Bill Johnson wrote:

It gets worse with all the new gadgets and LED lighting.  I just installed new 
plant lights, LEDs, and the racket from the wall warts is terrible.  I shut 
them off when operating, or not interested in lighting up the plants.  Terrible 
view of the noise on K4 graphic display.

Bill
K9YEQ

-Original Message-
From: elecraft-boun...@mailman.qth.net  On 
Behalf Of Jim Brown
Sent: Saturday, December 2, 2023 8:25 PM
To: elecraft@mailman.qth.net
Subject: Re: [Elecraft] Noise from KAT500?

On 12/2/2023 5:48 PM, W2HX wrote:

I then replaced the wall-wart power supply with a 12V battery. And
this is what I saw for BOTH bypass and inline. Clearly the problem.

https://w2hx.com/x/Elecraft/KAT500/Noise-Issue/KAT500-battery.png

using a battery, the noise is about -80 dBm. Using the wall-wart, in
some cases the noise is as high as -60 dBm



My task now is to either leave it on battery or preferably, find a low noise PS.


99.9% of stuff that plugs into the wall has a Switch-mode power supply, most of 
which are varying degrees of noisy. They were mandated to save energy about 20 
years ago, but thanks to small government, the FCC has no money to enforce 
their Rules that they be quiet. So they aren't.

A typical home has several dozen of them, either in the form of wall warts and 
line lumps or built into equipment and appliances. Rather than buying bigger 
and better anything for our station, our time and money is far better spent 
identifying and replacing as many as possible of these nasty noise sources.

There's a tutorial on my website, k9yc.com/publish.htm  about how to find and 
replace them. All of the 12V gear in my shack runs on two big batteries that 
are float charged by re-purposed Thinkpad power supplies using Genasun charge 
regulators. A 100Ah LiFePO4 runs the rigs, a 100Ah Sealed Lead Acid runs the 
rest of the stuff.

73, Jim K9YC

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Re: [Elecraft] Noise from KAT500?

[Jim Brown]

On 12/2/2023 7:33 PM, David Gilbert wrote:
Most of them have almost no reliable voltage regulation either. They are 
typically designed for a certain load, and if they don't see that load 
the voltage is much higher than rated.  I've tested dozens of these 
things (I tend not to throw anything away) and it's fairly typical that 
a 12 volt rated wall wart power supply presents 16 to 18 volts (or 
higher) no load.  That can be death to a piece of 12 volt gear that 
doesn't draw much current.


Exactly right, Dave! I discussed in detail in the tutorial. Nearly all 
of the warts, lumps, and the equipment they power are labeled with 
voltage and current. My advice in the tutorial, with pictures, is break 
the DC cable, add Power Poles, and use one of the inline volt-ammeters 
to confirm that the PSU is within the safe operating range of the unit 
being powered. In the 20 years I've been making these replacements, I've 
yet to blow anything up!


73, Jim K9YC


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Re: [Elecraft] Noise from KAT500?

[Bill Johnson]

It gets worse with all the new gadgets and LED lighting.  I just installed new 
plant lights, LEDs, and the racket from the wall warts is terrible.  I shut 
them off when operating, or not interested in lighting up the plants.  Terrible 
view of the noise on K4 graphic display.  

Bill
K9YEQ

-Original Message-
From: elecraft-boun...@mailman.qth.net  On 
Behalf Of Jim Brown
Sent: Saturday, December 2, 2023 8:25 PM
To: elecraft@mailman.qth.net
Subject: Re: [Elecraft] Noise from KAT500?

On 12/2/2023 5:48 PM, W2HX wrote:
> I then replaced the wall-wart power supply with a 12V battery. And 
> this is what I saw for BOTH bypass and inline. Clearly the problem.
> 
> https://w2hx.com/x/Elecraft/KAT500/Noise-Issue/KAT500-battery.png
> 
> using a battery, the noise is about -80 dBm. Using the wall-wart, in 
> some cases the noise is as high as -60 dBm
> 
> 
> 
> My task now is to either leave it on battery or preferably, find a low noise 
> PS.

99.9% of stuff that plugs into the wall has a Switch-mode power supply, most of 
which are varying degrees of noisy. They were mandated to save energy about 20 
years ago, but thanks to small government, the FCC has no money to enforce 
their Rules that they be quiet. So they aren't.

A typical home has several dozen of them, either in the form of wall warts and 
line lumps or built into equipment and appliances. Rather than buying bigger 
and better anything for our station, our time and money is far better spent 
identifying and replacing as many as possible of these nasty noise sources.

There's a tutorial on my website, k9yc.com/publish.htm  about how to find and 
replace them. All of the 12V gear in my shack runs on two big batteries that 
are float charged by re-purposed Thinkpad power supplies using Genasun charge 
regulators. A 100Ah LiFePO4 runs the rigs, a 100Ah Sealed Lead Acid runs the 
rest of the stuff.

73, Jim K9YC

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Re: [Elecraft] Noise from KAT500?

[David Gilbert]

The ones I measured just a couple of months ago were way too small and 
light to have a transformer in them, and they were horrible.  In any 
case, I recommend that anyone using a wall wart for other than its 
intended equipment (or any standalone new one) be sure to check it for 
both noise and no load voltage regulation.  It's quick and easy to do 
and could save a lot of headaches.


73,
Dave  AB7E



On 12/2/2023 9:09 PM, Victor Rosenthal 4X6GP wrote:
This is usually true of the linear type of wall-wart, which is the 
quiet kind! They generally are composed of just a transformer, 
rectifier, and capacitor.They are almost extinct these days, but I 
look for discarded ones for use with equipment for which it is safe to 
use an unregulated power source.
The switching types mostly are well-regulated, but of course they are 
often noisy.


73,
Victor, 4X6GP
Rehovot, Israel
formerly K2VCO
CWops no. 5
http://www.qsl.net/k2vco/

On 03/12/2023 5:33, David Gilbert wrote:


Most of them have almost no reliable voltage regulation either. They 
are typically designed for a certain load, and if they don't see that 
load the voltage is much higher than rated.  I've tested dozens of 
these things (I tend not to throw anything away) and it's fairly 
typical that a 12 volt rated wall wart power supply presents 16 to 18 
volts (or higher) no load.  That can be death to a piece of 12 volt 
gear that doesn't draw much current.


Dave   AB7E



On 12/2/2023 8:25 PM, Jim Brown wrote:


99.9% of stuff that plugs into the wall has a Switch-mode power 
supply, most of which are varying degrees of noisy. They were 
mandated to save energy about 20 years ago, but thanks to small 
government, the FCC has no money to enforce their Rules that they be 
quiet. So they aren't.


A typical home has several dozen of them, either in the form of wall 
warts and line lumps or built into equipment and appliances. Rather 
than buying bigger and better anything for our station, our time and 
money is far better spent identifying and replacing as many as 
possible of these nasty noise sources.


There's a tutorial on my website, k9yc.com/publish.htm  about how to 
find and replace them. All of the 12V gear in my shack runs on two 
big batteries that are float charged by re-purposed Thinkpad power 
supplies using Genasun charge regulators. A 100Ah LiFePO4 runs the 
rigs, a 100Ah Sealed Lead Acid runs the rest of the stuff.


73, Jim K9YC

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Re: [Elecraft] Noise from KAT500?

[Victor Rosenthal 4X6GP]

This is usually true of the linear type of wall-wart, which is the quiet 
kind! They generally are composed of just a transformer, rectifier, and 
capacitor.They are almost extinct these days, but I look for discarded 
ones for use with equipment for which it is safe to use an unregulated 
power source.
The switching types mostly are well-regulated, but of course they are 
often noisy.


73,
Victor, 4X6GP
Rehovot, Israel
formerly K2VCO
CWops no. 5
http://www.qsl.net/k2vco/

On 03/12/2023 5:33, David Gilbert wrote:


Most of them have almost no reliable voltage regulation either. They are 
typically designed for a certain load, and if they don't see that load 
the voltage is much higher than rated.  I've tested dozens of these 
things (I tend not to throw anything away) and it's fairly typical that 
a 12 volt rated wall wart power supply presents 16 to 18 volts (or 
higher) no load.  That can be death to a piece of 12 volt gear that 
doesn't draw much current.


Dave   AB7E



On 12/2/2023 8:25 PM, Jim Brown wrote:


99.9% of stuff that plugs into the wall has a Switch-mode power 
supply, most of which are varying degrees of noisy. They were mandated 
to save energy about 20 years ago, but thanks to small government, the 
FCC has no money to enforce their Rules that they be quiet. So they 
aren't.


A typical home has several dozen of them, either in the form of wall 
warts and line lumps or built into equipment and appliances. Rather 
than buying bigger and better anything for our station, our time and 
money is far better spent identifying and replacing as many as 
possible of these nasty noise sources.


There's a tutorial on my website, k9yc.com/publish.htm  about how to 
find and replace them. All of the 12V gear in my shack runs on two big 
batteries that are float charged by re-purposed Thinkpad power 
supplies using Genasun charge regulators. A 100Ah LiFePO4 runs the 
rigs, a 100Ah Sealed Lead Acid runs the rest of the stuff.


73, Jim K9YC

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Re: [Elecraft] Noise from KAT500?

[David Gilbert]

Most of them have almost no reliable voltage regulation either. They are 
typically designed for a certain load, and if they don't see that load 
the voltage is much higher than rated.  I've tested dozens of these 
things (I tend not to throw anything away) and it's fairly typical that 
a 12 volt rated wall wart power supply presents 16 to 18 volts (or 
higher) no load.  That can be death to a piece of 12 volt gear that 
doesn't draw much current.


Dave   AB7E



On 12/2/2023 8:25 PM, Jim Brown wrote:


99.9% of stuff that plugs into the wall has a Switch-mode power 
supply, most of which are varying degrees of noisy. They were mandated 
to save energy about 20 years ago, but thanks to small government, the 
FCC has no money to enforce their Rules that they be quiet. So they 
aren't.


A typical home has several dozen of them, either in the form of wall 
warts and line lumps or built into equipment and appliances. Rather 
than buying bigger and better anything for our station, our time and 
money is far better spent identifying and replacing as many as 
possible of these nasty noise sources.


There's a tutorial on my website, k9yc.com/publish.htm  about how to 
find and replace them. All of the 12V gear in my shack runs on two big 
batteries that are float charged by re-purposed Thinkpad power 
supplies using Genasun charge regulators. A 100Ah LiFePO4 runs the 
rigs, a 100Ah Sealed Lead Acid runs the rest of the stuff.


73, Jim K9YC

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Re: [Elecraft] Noise from KAT500?

[Jim Brown]

On 12/2/2023 5:48 PM, W2HX wrote:

I then replaced the wall-wart power supply with a 12V battery. And this
is what I saw for BOTH bypass and inline. Clearly the problem.

https://w2hx.com/x/Elecraft/KAT500/Noise-Issue/KAT500-battery.png

using a battery, the noise is about -80 dBm. Using the wall-wart, in some cases 
the noise is as high as -60 dBm



My task now is to either leave it on battery or preferably, find a low noise PS.


99.9% of stuff that plugs into the wall has a Switch-mode power supply, 
most of which are varying degrees of noisy. They were mandated to save 
energy about 20 years ago, but thanks to small government, the FCC has 
no money to enforce their Rules that they be quiet. So they aren't.


A typical home has several dozen of them, either in the form of wall 
warts and line lumps or built into equipment and appliances. Rather than 
buying bigger and better anything for our station, our time and money is 
far better spent identifying and replacing as many as possible of these 
nasty noise sources.


There's a tutorial on my website, k9yc.com/publish.htm  about how to 
find and replace them. All of the 12V gear in my shack runs on two big 
batteries that are float charged by re-purposed Thinkpad power supplies 
using Genasun charge regulators. A 100Ah LiFePO4 runs the rigs, a 100Ah 
Sealed Lead Acid runs the rest of the stuff.


73, Jim K9YC

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Re: [Elecraft] Noise from KAT500?

[W2HX]

Mike, K8CN wins the cigar!



The issue is the power supply ☹ I took some spectrum analyzer plots to 7 MHz 
and you can see what I saw. The set up is spectrum analyzer -> KAT500 -> Dummy 
Load. First picture are two "max hold" traces superimposed where the problem 
can be seen.

https://w2hx.com/x/Elecraft/KAT500/Noise-Issue/KAT500-AC-Power.png

The "lower" trace is what I saw with the kat500 in bypass. The "top" trace is 
with the kat500 inline (auto or manual).



I then replaced the wall-wart power supply with a 12V battery. And this is what 
I saw for BOTH bypass and inline. Clearly the problem.

https://w2hx.com/x/Elecraft/KAT500/Noise-Issue/KAT500-battery.png

using a battery, the noise is about -80 dBm. Using the wall-wart, in some cases 
the noise is as high as -60 dBm



My task now is to either leave it on battery or preferably, find a low noise PS.



Thanks everyone for the ideas.



73 Eugene W2HX

Subscribe to my Youtube Channel: https://www.youtube.com/@w2hx/videos



-Original Message-
From: elecraft-boun...@mailman.qth.net  On 
Behalf Of Michael Carter via Elecraft
Sent: Saturday, December 2, 2023 5:52 PM
To: Elecraft Reflector Reflector 
Subject: Re: [Elecraft] Noise from KAT500?



Hi Eugene,



Are you using a switch-mode power supply to feed the KAT500?  If so, try a 
linear regulator supply or a battery instead.



Is your KAT500 bonded to your other station equipment and AC ground with a 
short, wide conductor? (not just the coax shields)



Since you're not the original constructor of the KAT500, I would check inside 
the case to be sure that the case sections have the powder coat removed where 
circuit board standoffs and case section screws are placed.



What kind of cable do you use to connect the KAT500 to your shack computer?  
One should NOT use a standard VGA cable as the manual makes clear.



73,

Mike, K8CN

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Re: [Elecraft] Noise from KAT500?

[Michael Carter via Elecraft]

One more thing to check, Eugene:

Are the other two antenna ports
on the KAT500 connected to
anything?  If so, disconnect
those ports other than the one
you used in your video demonstration.

73,
Mike,
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Re: [Elecraft] Noise from KAT500?

[Michael Carter via Elecraft]

Hi Eugene,

Are you using a switch-mode power supply
to feed the KAT500?  If so, try a linear regulator
supply or a battery instead.

Is your KAT500 bonded to your other station
equipment and AC ground with a short, wide
conductor? (not just the coax shields)

Since you're not the original constructor of
the KAT500, I would check inside the case
to be sure that the case sections have the
powder coat removed where circuit board
standoffs and case section screws are placed.

What kind of cable do you use to connect
the KAT500 to your shack computer?  One
should NOT use a standard VGA cable as
the manual makes clear.

73,
Mike, K8CN
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Re: [Elecraft] Noise from KAT500?

[Ken Winterling]

Eugene,

This may or may not address your issue but the KAT500 user manual reports
that a signal may be heard from an oscillator in the unit. The manual
advises that this can be shut down when not in use by running the KAT500
Utility.

Below is the reference to Idle Sleep in the manual.


*Idle SleepIn some installations a 28004.5 MHz signal may be heard from an
oscillator in the KAT500. If this is an issue, you can cause the KAT500
oscillator to shut down when it is not needed. Click on Idle Sleep to put a
check in the radio button. The oscillator will stop running shortly after
the last key press or the last data communication with other equipment and
restart automatically when needed.*

*Ken*
*WA2LBI*




On Sat, Dec 2, 2023 at 5:14 PM W2HX  wrote:

> Hello all,
>
> I have my new (to me) KAT500 up and running but I am noticing it is
> introducing quite a lot of noise when "inline" but the noise is gone in
> "bypass."
> Here is a video I made of the situation. The video shows the issue on 60m,
> but I will note, that I also checked the situation on 20m and it is the
> same. The problem is significant and might prohibit me from using the
> KAT500.
>
> Anyone know what might be going on?
> https://youtu.be/5EvByZDYI3g
>
>
> 73 Eugene W2HX
> Subscribe to my Youtube Channel: https://www.youtube.com/@w2hx/videos
>
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